v3.25.4
Retirement Benefits (Schedule of Net Periodic Benefit Cost Not yet Recognized) (Details) - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Consumers Energy Company    
Regulatory assets    
Total regulatory assets $ 3,459 $ 3,798
DB Pension Plans and DB SERP    
Regulatory assets    
Net loss 548 653
Prior service cost (credit) 9 12
Total regulatory assets 557 665
AOCI    
Net loss (gain) 57 60
Prior service credit 0 0
Total amounts recognized in regulatory assets and AOCI 614 725
DB Pension Plans and DB SERP | Consumers Energy Company    
Regulatory assets    
Net loss 548 653
Prior service cost (credit) 9 12
Total regulatory assets 557 665
AOCI    
Net loss (gain) 18 15
Total amounts recognized in regulatory assets and AOCI 575 680
OPEB Plan    
Regulatory assets    
Net loss 93 176
Prior service cost (credit) (61) (94)
Total regulatory assets 32 82
AOCI    
Net loss (gain) (7) (3)
Prior service credit (2) (2)
Total amounts recognized in regulatory assets and AOCI 23 77
OPEB Plan | Consumers Energy Company    
Regulatory assets    
Net loss 93 176
Prior service cost (credit) (61) (94)
Total regulatory assets 32 82
AOCI    
Net loss (gain) 0 0
Total amounts recognized in regulatory assets and AOCI $ 32 $ 82